Fireworks lighting up the sky over National Harbor to celebrate the Question 7 ballot vicory on Tuesday. (Mark Gail/For The Washington Post)

Shortly before midnight Tuesday, after it had become clear that Maryland voters had approved a casino in Prince George’s County, the developers of National Harbor celebrated with fireworks.

But on Wednesday, it was back to business as usual in the mini-city on the Potomac. That is to say, not much business at all.

Half-empty restaurants, largely vacant parking garages and customerless boutiques are often the norm in the created-from-scratch community, which for years has embodied the struggles and the hopes of Prince George’s.

But county officials and the developers of National Harbor say they believe that Tuesday’s vote will help change all that. The measure, which passed narrowly after a relentless $90 million campaign, would allow table games at Maryland’s five designated slot machine sites and permit a full-fledged casino in Prince George’s.

MGM Resorts, which has built casino-hotels around the world, including several on the Las Vegas strip, is angling to build what it has promised would be an $800 million high-end, luxury resort that would open on the Potomac by 2016.

MGM officials boasted that it would become a destination for residents and tourists and attract Rodeo Drive-worthy retail (Fendi, Louis Vuitton, Hermes) and Vegas-style entertainment (Madonna, Saturday night fights).

Prince George’s officials, including County Executive Rushern L. Baker III (D), said that it could become the economic and cultural mecca — 20 minutes or so from downtown Washington — that the county has sought for more than a decade.

“Having a destination resort will help Prince George’s County. It will help the state,” Baker said, estimating that the county might take in $40 million a year from the casino, revenue that could give a boost to its $2.7 billion annual budget.

Because Prince George’s operates under a voter-imposed property tax cap, public officials are often scrambling for funds, and its school system — about the same size as nearby Montgomery County’s — has a budget that is a third less than Montgomery’s school budget.

But as proponents of expanded gambling celebrated their victory Wednesday and looked forward to decisions on where the casino would be located and who would be licensed to operate it, opponents refused to give up the fight.

Former County Council member Thomas E. Dernoga (D-Laurel), a lawyer and a longtime opponent of gambling, filed a lawsuit last week on behalf of several community activists challenging the way votes are counted in the referendum process. Penn National Gaming, which hopes to acquire a license for a casino at Rosecroft Raceway in nearby Fort Washington, is also questioning the referendum process. The company has complained that the license is a done deal for MGM.

The final decision on who gets the license in Prince George’s, and where the casino will be located, is up to a state commission.

Critics of the plan have said the potential benefit to the county and the state may have been exaggerated, and they question the promise of officials to use the money to support education.

But as federal jobs continue to dwindle across the Washington region, experts say a new and more diverse economic order needs to rise up. Gambling, the hospitality business and retail all may play a larger role.

“People who might not go there to gamble will put it on their scorecard,” said economist Stephen Fuller, director of the Center for Regional Analysis at George Mason University. “I don’t think that this is going to have an enormous impact on the regional economy, but people who might not have stopped otherwise will go there. It is not going to remake Prince George’s, but it will be positive.”

Fuller said Prince George’s should do more about other opportunities. He pointed to the unexploited potential of the University of Maryland to spin off tech businesses and business service companies. “I do not see the casino as being the epicenter of the economy,” he said, “but I do see the university that way. The casino is fine, but it isn’t the answer. I don’t think it is a long-term strategy that Prince George’s County can rest on.”

Although the casino may offer an economic boost to Prince George’s, David Iannucci, who spearheads economic development efforts for the county, said he will press to diversify the county’s commercial tax base. “That is an important part of our plans,” he said.

How much revenue will flow to Prince George’s and Maryland from a casino won’t be known for some time. And the costs of the associated social ills — ills that even MGM acknowledges accompany casinos — cannot yet be quantified.

Still, the promise of a casino and all that it might bring has been welcomed by many National Harbor businesses, which on most weekdays sit nearly empty as workers wait anxiously for the next customer.

At Fiorella Pizzeria, a sit-down restaurant in National Harbor, floor supervisor Bianca Johnson was hopeful.

“It’s an awesome thing for the National Harbor,” said Johnson, whose restaurant on Wednesday was serving about a dozen patrons at lunchtime. Most tables were empty.

“It’s going to bring a lot of business.”

Elisa Rafter, gallery director at Art Whino, said the casino will be a plus even though it might not affect the gallery’s business.

“It’s another incentive for people to come to the harbor,” Rafter said. “It could become more of an adult’s playground.”

She also hopes it might lead to better transportation to and from National Harbor, which is now reached mostly by car, taxi and water taxi.

“Right now, we’re this little island. Even if you live in Prince George’s County, you can’t walk here. They built this whole area, but you can’t really get to it.”

For Prince George’s County Council member William A. Campos (D-Hyattsville), the arrival of upscale retail and dining would be welcome.

The casino? “I am not a gambler,” he said. “But we don’t even have a Nordstrom.”